FreeBSD: How To boot kernel.old

If you want to boot with an old kernel, because the current one is not working properly, this is what you have to do:
During boot you get a message like:
"Booting kernel in 10 seconds or press enter..."
Just hit any key except the ENTER key and you'll get a prompt.
Type 'unload all' and then 'boot [kernel file]' where [kernel file] is the kernel you want
to boot e.g. 'kernel.old' .

Your FreeBSD machine will boot with the kernel you specified.